Added LocalWorld.fixLighting(Set<BlockVector2D>)

This method redos lighting in the given chunks.
BukkitWorld's current implementation introduces some slight errors and doesn't redo torch light, but it's better than nothing.

src/main/java/com/sk89q/worldedit/LocalWorld.java

@@ -325,4 +325,6 @@ public abstract class LocalWorld {
     public int getHeight() {
         return 127;
     }
+
+    public void fixLighting(Iterable<BlockVector2D> chunks) {}
 }